A technique is known in which the eyesight direction of a user is detected by emitting non-visible light such as near-infrared light to the user's eyes, and analyzing an image of the user's eyes including reflected light. Information of the detected eyesight direction of the user is reflected on the monitor of, for example, a PC (Personal Computer), a game console or the like, and thus use as a pointing device has been realized.
A head mounted display is an image display device that presents a three-dimensional image to a user wearing the device. Generally, the head mounted display is used in a state of being mounted to cover the visual range of a user. For this reason, a user wearing the head mounted display has an external image shielded. When the head mounted display is used as a display device of an image of a moving picture, a game or the like, it is difficult for a user to visually recognize an input device such as a controller.
Therefore, the usability of a head mounted display as a substitute for a pointing device by detecting the eyesight direction of a user wearing the display is of convenience. Particularly, the acquisition of geometric information (information of spatial coordinates or a shape) of a user's cornea in a state where the user wears a head mounted display is useful in estimating the eyesight direction of the user.
It could therefore be helpful to provide a technique of detecting geometric information of the cornea of a user wearing a head mounted display.